fix(license): add .gitignore to REUSE defaults

36 packages use this while 26 use *.pam and 21 use *.logrotate. Seems
anecdotally common enough to add this here.

src/lib/license/setup.sh

@@ -188,6 +188,7 @@ path = [
     "README.md",
     "keys/**",
     ".SRCINFO",
+    ".gitignore",
     ".nvchecker.toml",
     "*.install",
     "*.sysusers",